Magnetic resonance imaging and histopathology of catheter ablation lesions after ventricular tachycardia ablation in patients with nonischemic cardiomyopathy.

Abstract

Late gadolinium enhanced cardiac magnetic resonance (LGE-CMR) imaging may help identify radiofrequency ablation lesions, which have been poorly described in patients with nonischemic cardiomyopathy (NICM). The purpose of this study was to describe LGE-CMR characteristics of ablation lesions in patients with NICM and correlate them with histopathology. Twenty-six patients (24 men; ejection fraction 38% ± 14%; age 61 ± 9 years) who had undergone CMR imaging after ventricular tachycardia (VT) ablation were included. Areas of both dark and bright core lesions correlating with previous radiofrequency ablation lesions were identified. Histology was performed on an explanted heart. Mean time between the ablation procedure and the LGE-CMR study was 8 [2-20] months. Twenty-three of 26 patients demonstrated dark core lesions (volume 2.16 ± 1.8 cm3; thickness 3.6 ± 1.3 mm) with transmurality of 42% ± 16% overlaying areas of intramural or transmural LGE. Fourteen of 26 patients demonstrated bright core lesions (volume 0.8 ± 0.6 cm3; depth 4.15 ± 1.76 mm) with transmurality of 34% ± 14%, which was located in areas without underlying LGE in 11 of 13 patients. Both dark and bright core lesions were visualized on standard clinical LGE-CMR imaging obtained in the acute setting and chronic settings (within 3 days and up to 2090 days postablation). Histopathologic analysis demonstrated coagulation necrosis in the area that corresponded to dark core lesions in the postablation CMR. Ablation lesions can be detected by LGE-CMR after VT ablation in NICM patients and have a different appearance than scar tissue. These lesions can be observed in the acute and chronic settings after ablations.